Spark plug anti-foulant

ABSTRACT

A method of reducing spark plug fouling in spark ignition engines fueled with organomanganese containing gasoline is described. The method features the use in gasoline of a spark plug antifouling amount of an organic molybdenum compound. Molybdenum naphthenate is an example of a useful antifoulant compound.

Inventor Vincent 1F. lllnizda Huntington Woods, Mich. Appl. No. 785,801 Filed Dec. 20, 1968 Patented Oct. 26, 11971 Assignee lEtlhyI Corporaiion New Yorlr, N311.

SlPAlRlK lPlLUG ANTH-FOUILANT 21 Claims, No Drawings [56] References Cited UNITED STATES PATENTS 2,737,932 3/1956 Thomas 44/68 X 2,881,062 4/1959 Bishop... 44/69 2,913,413 11/1959 Brown 44/68 X 3,003,859 10/1961 lrish et al. 44/68 3,127,351 3/1964 Brown etal... 44/68 X 3,481,719 12/1969 Patinkin 44/68 X Primary Examiner- Daniel E. Wyman Assistant Examinerw. J. Shine At!0rney-D0nald L. Johnson ABSTRACT: A method of reducing spark plug fouling in spark ignition engines fueled with organomanganese containing gasoline is described. The method features the use in gasoline of a spark plug antifouling amount of an organic molybdenum compound.

Molybdenum naphthenate is an example ofa useful antifoulam compound.

BACKGROUND OF THE INVENTKON The invention is directed to improving the operation of an internal combustion engine fueled with gasoline containing organomanganese antiknock. The improvement lies in the addition to said fuel of an organic molybdenum compound.

Cyclopentaclienyl manganese tricarbonyls are known to be effective gasoline antiknock agents, Cf. U.S. Pat. No. 3,127,351, issued Mar. 31, 1964. It is also known that in using fuels containing these manganese compounds in spark ignition internal combustion engines a problem can arise from manganese forming deposits on spark plug ignition surfaces. This tendency to build up such deposits on the spark plug is commonly referred to as spark plug fouling. Spark plug fouling reduces the efficiency of engine operation. Nonmetallic phosphates and xanthates have been disclosed as useful additives to reduce spark plug fouling tendencies of such manganese containing fuels. (Cf. "New Antiknock lFor Gasoline, A. A. Gureeva, p. 5862, Ts. N.l.l.T.lE. letroleumgas, Moscow (1963); and Russian Pat. No. 161,844.

The present invention provides a novel metallic additive which quite unexpectedly reduces spark plug fouling when using fuels containing the aforesaid organomanganese compounds.

SUMMARY OF THE lNVENTlON A method of reducing spark plug fouling in internal combustion engines fueled with gasoline characterized by being substantially free of tetrahydrocarbyl lead antiknock agents containing an organomanganese antiknock, by adding to said gasoline prior to ignition an organic molybdenum compound; the gasoline compositions containing the organomangancse compound and the molybdenum spark plug antifoulant.

DESClRlPTlON OF THE PREFERRED EMBODIMENT An embodiment of this invention is a method of reducing spark plug fouling in internal combustion engines when burning gasoline which is substantially free of tetrahydrocarbyl lead antiknocks and contains a manganese antiknock compound by adding to said gasoline prior to burning a spark plug antifoulant amount of a molybdenum compound. ln a preferred embodiment the manganese antiknock is a cyclopentadienyl manganese tricarbonyl wherein said cyclopentadienyl group has up to 13 carbon atoms and said molybdenum compound is an organic molybdenum compound selected from the group consisting of l. molybdenum chelates 2. molybdenum salts of a. phenol and C C alkyl substituted phenols b. phosphoric acids having the formula wherein X, X, X and X are independently selected from O and S and R and R, are independently selected from hydrocarbon alkyl and aryl groups having from one to about 30 carbon atoms.

c. hydrocarbon carboxylic acids having from five to about 24 carbon atoms, and

d. naphthenic acids. An amount of the manganese antiknock and the molybdenum compound sufficient to provide an atomic ratio of manganesezmolybdenum (MmMo) of about 1:1 to about 1:0.05 is also preferred; molybdenum naphthenate is an especially preferred molybdenum additive. These and other embodiments of the present invention will be made clear by the description which follows.

Any gasoline suitable for use in internal combustion engines may be used in the practice of this invention provided it is substantially free of tetrahydrocarbyl lead compounds such as tetraethyl lead and the like. By gasoline is meant a hydrocarbon or blend of hydrocarbons boiling in the range from about 25 C. to about 250 C. which occur naturally in petroleum as well as suitable hydrocarbons manufactured from petroleum, for example, by thermal or catalytic cracking, polymerizing, reforming, and the like. Typical gasolines are listed in table l.

TABLE l Hydrocarbon Composition of Base Gasolines As pointed out above, the gasolines are characterized as being substantially free of tetrahydrocarbyl antiknock Compounds. ln the course of handling gasolines in refinery operations and the like, base gasolines may pick up trace amounts of tetrahydrocarbyl antiknock compounds. These trace amounts are generally less than about 0.1 grams of Pblgallon as the tetrahydrocarbyl lead compound. Thus the term substantially free of tetrahydrocarbyl lead antiknock agents, include such base gasolines including such trace amounts of lead.

Manganese compounds which are useful as antiknock agents in gasoline compositions of the present invention are cyclopentadienyl manganese tricarbonyls having the formula RMMCO], wherein R is a cyclopentadienyl hydrocarbon radical having from five to 13 carbon atoms. Useful compounds are exemplified by cyclopentadienyl manganese tricarbonyl, indenylmanganese tricarbonyl, diethylcyclopentadienyl manganese tricarbonyl, 4-tert-butylindcnyl manganese tricarbonyl and isopropylcyclopentadienyl manganese tricarbonyl. U.S. Pat. No. 3,167,351 issued Mar. 31, 1964, contains an extensive disclosure of the type of manganese compounds which are useful, This disclosure of compounds is incorporated by reference.

(Methylcyclopentadienyl)rnanganese tricarbonyl is an especially effective antiknock agent.

The concentration of the manganese tricarbonyl in the gasoline may be varied. Concentrations from 0.5 to about 6.0 grams of manganese per gallon as a cyclopentadienyl manganese tricarbonyl are useful.

Molybdenum compounds which are useful in the present invention are organic, gasoline soluble or gasoline dispersible compounds. They include molybdenum salts and chelates. Organic molybdenum compounds which are gasoline soluble are preferred; by gasoline soluble is meant sufficient solubility in gasoline to effect spark plug antifouling as herein described.

One class of useful organic molybdenum compounds are molybdenum chelates. These chelates are coordination compounds in which a central molybdenum atom is joined to two or more atoms of one or more other molecules or ions (called ligands) so that one or more heterocyclic rings are formed with the central molybdenum atom as part of each ring. Examples of these compounds are chelate complexes of molybdenum with acetylacetone, N-nitro sophenylhydroxylamine, dimethylglyoxime, ethylenediamine, ethylenediaminetetraacetic acid, nitrilotriacetic acid, 8- hydroxyquinoline, benzoylacetone, 2,4-pentanediene, 4- rnethylamino-2-buten'2-ol, and similar chelating agents.

Another class of useful organic compounds are the molybdenum phenates. These are salts of molybdenum and phenol or substituted phenols, and especially C,C alkylphenols.

The simplest member of this class of compounds is molybdenum phenate; representative formula for molybdenum phenates are Mo(O-Ph), and wherein x is an integer from 2-6 inclusive and Ph is the phenyl or substituted phenyl group.

Salts of molybdenum and the following phenols are useful 4-methylphenol 4-octadecylphenol 4-oleylphenol 4-(2-ethyl-n-hexyl)phenol 2.6-dimethylphenol 2,4,6-trimethylphenol o-chlorophenol 2-dodecylphenol 2,4-didodecylphenol l5 n-nonylphenol 2-tert-butylphenol 3-nitrophenol and the like.

An especially useful type of a molybdenum phenate is that derived from a commercial mixture of alkylated phenols. Commercial alkylation of phenols generally is accomplished by treating the phenol with an olefin or a mixture of olefins in the presence of an alkylating agent. This commercial alkylation ordinarily produces a mixture of various alkyl phenols. For example, if a phenol is alkylated with a C olefin, the product will contain monononylphenols, dinonylphenols, and trinonylphenols. Likewise, if a mixture of C C C olefins is used in the alkylation, a mixture of various C C and C alkylated phenols is obtained. Molybdenum salts of these commercial mixtures of alkylated phenols wherein the alkyl groups have from three to about 18 carbon atoms are also useful in the present invention.

Another class of useful compounds are molybdenum salts of hydrocarbon substituted phosphoric acids; these include the thiophosphoric acids. These phosphoric acids are represented by the following formula wherein X, X, X and X can be 0 and/or S and R and R,, are hydrocarbyl groups. Hydrocarbyl groups are hydrocarbon alkyl and aryl groups; hydrocarbyl groups having from one to about 30 carbon atoms are useful. Examples of molybdenum salts of acids offormula l are S-molybdenum-0,0 -dimethylphosphorothioate O-molybdenum-O,0"-dioctylphosphorothioate molybdenum diphenylphosphate molybdenum dicresylphosphate S-molybdenum-O,S-didecylphosphorodithioate molybdenum diamylphosphorotetrathioate O-molybdenum-S,S'-di-tert-butylphosphorotrithioate O-molybdenum-O',O"-dixylylphosphorothioate S-molybdenum-S'-di-,S"4-ethylphenylphosphorotrithioate 60 molybdenum dioctadecylphosphorotetrathioate molybdenum cresylphenylphosphate O-molybdenum-O,0"-dinaphthylphosphorothioate S-molybdenum-O"'-diisopropylphosphorothioate molybdenum dibenzylphosphate and the like. Salts of dithiophosphoric acids where two of X, X, X and X in formula I are S are preferred. Examples of preferred salts are S-molybdenum-0,0'-dimethylphosphorodithioate S-molybdenum-0,0'-dicresylphosphorodithioate S-molybdenum-0,0-di-4-dodecylphenylphosphorodithioate S-molybdenum-0,0'-dibenzylphosphorodithioate S-molybdenum-0,0'-dilaurylphosphorodithioate S-molybdenum-0,0-di-2-ethylhexylphosphorodithioate anoate, molybdenum benzoate, molybdenum tetradecanoate,

molybdenum orthopthalate, molybdenum-4-dodecylbenzoate, molybdenum stearate, molybdenum laurate and the like. Molybdenum salts of mixtures of fatty acids obtained from natural products such as olive oil, babassu oil, tall oil, cotton seed oil, tallow, coconut oil and the like are also useful. More preferred molybdenum compounds of this type are the salts of alicyclic carboxylic acids. Specific examples of useful molybdenum salts of alicyclic carboxylic acids are molybdenum cyclopentanecarboxylate, molybdenum cyclopentylacetate, molybdenum 3-methylcyclopentylacetate, molybdenum camphonanate, molybdenum cyclohexanecarboxylate, molybdenum 3-dodecylcyclohexanecarboxylate, molybdenum 2,6- di-cyclohexylcyclohexane carboxylate, molybdenum 2- cyclohexyl-4,6-dipentyl-4-methylcyclohexanecarboxylate, molybdenum 4-methylcyclohexanecarboxylate, molybdenum 2,2,6-trimethylcyclohexane carboxylate and the like.

An especially preferred class of organic molybdenum salts are salts of the so-called naphthenic acids. The term naphthenic acids" is applied to a mixture of carboxylic acids obtained from the alkali washes of petroleum. These acids are complex mixtures of normal and branched aliphatic acids, alkyl derivatives of cyclopentane and cyclohexane carboxylic acids and cyclopentyl and cyclohexyl derivatives of aliphatic acids. The alicyclic carboxylic acids appear to be the major constituents of these mixtures. The composition of these naphtenic acids will vary depending on factors such as the source of petroleum, the refining procedure, etc. A more detailed discussion of these naphthenic acids is presented in Chemical Technology of Petroleum," William A. Gruse and Donald R. Stevens, 3rd edition, pgs. 65-67, 1960, McGraw- Hill Publishing Company; and is incorporated by reference.

For commercial use, the crude naphthenic acid mixture ob tained in the alkali extract is generally refined to remove unsaponifiable material. Molybdenum salts of either the crude naphthenic acid mixture or of the refined naphthenic acid mixture are useful in the present invention. The molybdenum salts of the refined naphthenic acids are especially preferred; the term molybdenum naphthenate will be used herein to describe these especially preferred salts.

The amount of organic molybdenum compounds described above which is added to the organomanganese containing fuel may be varied. In general, sufficient organic molybdenum compound is added to the fuel so that the atomic ratio of manganese (Mn): molybdenum (M0) is from about lzl to about 1:0.05.

The fuels used in the present invention can be prepared by adding the required manganese and molybdenum compounds directly to the gasoline which is substantially free of tetrahydrocarbyl lead antiknock agents. No special preparution appears to be required; conventional blending equipment can be used. If desired, the manganese and molybdenum compounds can be premixed to form a concentrate, commonly called an additive fluid, for addition to the gasoline. These concentrates containing the molybdenum and manganese compounds are another embodiment of this invention.

Other gasoline additives such as dyes, antioxidants such as alkylated phenols, diamines, phosphites and the like, metal deactivators such as N,N'-disolicylidene-1,2-diaminopropane and the like, carburetor detergents such as fatty acid amides, anti-icers, methylcarbitol and the like, corrosion inhibitors such as linoleic acid dimer and the like can also be present in the gasoline compositions of the present invention; these additives can, if desired, also be added as concentrate mixes or additive fluids to the gasoline composition.

The following examples illustrate fuels which are useful in the present invention. The molybdenum naphthenate used in examples lis a commercial product, Nuodex"Mo1ybdenum Naphthenate, which is reported by the manufacturer to contain 5 percent by weight of molybdenum.

EXAMPLE 1 To isooctane was added 2.0 grams per gallon of manganese as (methylcyclopentadienyl)manganese tricarbonyl and0.25 grams per gallon of molybdenum as molybdenum naphthenate.

The MnzMo atomic ratio of this fuel is about 1:0.07.

EXAMPLE 2 An additional 0.25 grams per gallon of molybdenum as molybdenum naphthenate was added to the example 1 fuel composition.

The MnzMo atomic ratio of this fuel is about 1:0.14.

EXAMPLE 3 To base gasoline C is added 2.0 grams per gallon of manganese as (methylcyclopentadieny1)manganese tricarbonyl and 3.6 grams per gallon of molybdenum as molybdenum naphthenate.

The Mn:Mo atomic ratio ofthis fuel is about 1:1.

EXAMPLE 4 To base gasoline F is added 1.0 grams per gallon of manganese as cyclopentadienylmanganese tricarbonyl and 0.9 grams per gallon of molybdenum as molybdenum naphthenate.

The MnzMo atomic ratio of this fuel is about 1:05.

EXAMPLE 5 To base gasoline G is added 3.0 grams per gallon of manganese as terl-butylindenylmanganese tricarbonyl and 0.27

grams per gallon of molybdenum as molybdenum naphthenate.

The MnrMo atomic ratio of this fuel is about 1:0.05.

EXAMPLE 6 EXAMPLE 7 To base gasoline A is added 0.8 grams per gallon of manganese as cyclopentadienylmanganese tricarbonyl and 0.79 grams per gallon of molybdenum as molybdenum/acetylacetone chelate.

The MnzMo atomic ratio ofthis fuel is about 1:0.55.

EXAMPLE 8 To base gasoline B is added 6.0 grams per gallon of manganese as ethylcyclopentadienylmanganese tricarbonyl and 0.54 grams per gallon of molybdenum as molybdenum/8- hydroxyquinoline chelate.

The Mn:Mo atomic ratio of this fuel is about 1:0.05.

EXAMPLE 9 To base gasoline C is added 5.0 grams per gallon of manganese as indenylmanganese tricarbonyl and 6.3 grams per gallon of molybdenum as molybdenum/1,3-propylene diamine chelate.

The MnzMo atomic ratio of this fuel is about 1:07.

EXAMPLE To base gasoline D is added 4.0 grams per gallon of manganese as cyclopentadienylmanganese tricarbonyl and 2.1 grams per gallon of molybdenum as molybdenum benzoate.

The MnzMo atomic ratio ofthis fuel is about 1:03.

EXAMPLE 1. 1

To base gasoline E is added 3.0 grams per gallon of manganese as ethylcyclopentadienylmanganese tricarbonyl and 5.4 grams per gallon of molybdenum as molybdenum diphenyl hydrogen phosphate.

The Mn:Mo atomic ratio of this fuel is about 1:1.

EXAMPLE 12 To base gasoline F is added 2.0 grams per gallon of manganese as (isopropylcyclopentadienyl)manganese tricarbonyl and 1.4 grams per gallon of molybdenum as molybdenum phenate.

The Mn:Mo atomic ratio of this fuel is about 1:04.

EXAMPLE 13 To base gasoline G is added 1.0 grams per gallon of manganese as (ethylcyclopentadienyl)manganese tricarbonyl and 1.0 grams per gallon of molybdenum as molybdenum 4-octadecylphenatc.

The MnzMo atomic ratio ofthis fuel is about 120.6.

EXAMPLE 14 To base gasoline A is added 0.5 grams per gallon of manganese as (methylcyclopentadienyl)manganese tricarbonyl and 0.2 grams per gallon of molybdenum as molybdenum 2,4- diisopropylphenate.

The MnzMo atomic ratio of this fuel is about 1:02.

EXAMPLE 15 To base gasoline 0 is added 0.6 grams per gallon of manganese as indenylmanganese tricarbonyl and 0.11 grams per gallon of molybdenum as -O-molybdenum,0',0"-ditriacontylphosphorothioate.

The MnzMo atomic ratio of this fuel is about 120.1.

EXAMPLE 16 To base gasoline C is added 2.5 grams per gallon of manganese as (dimethylcyclopentadienyl)manganese tricarbonyl and 4.0 grams per gallon of molybdenum as S-molybdenum- 0,0'-di-tert-butylphosphorodithioate.

The Mn:Mo atomic ratio of this fuel is about 1:09.

EXAMPLE 17 To base gasoline D is added 3.5 grams per gallon of manganese as (2-methy1indenyl)manganese tricarbonyl and 5.0 grams per gallon of molybdenum as S-molybdenum-O,S'- dimethylphosphorotrithioate.

The MncMo atomic ratio ofthis fuel is about 110.8.

To base gasoline E is added 4.5 grams per gallon of manganese as (diisopropylcyclopentadienyl)manganese tricarbonyl and 1.2 grams per gallon of molybdenum as molybdenum didocylphosphorotetrathioate.

The MnzMo atomic ratio of this fuel is about 1:0.15.

EXAMPLE 19 To base gasoline F is added 5.5 grams per gallon of manganese as (hexylcyclopentadienyl)manganese tricarbonyl and 2.5 grams per gallon of molybdenum as molybdenum cyclopentane carboxylate.

The MnzMo atomic ratio of this fuel is about 1:0.25.

EXAMPLE 20 To base gasoline G is added 1.5 grams per gallon of manganese as fluorenylmanganese tricarbonyl and 1.3 grams per gallon of molybdenum as molybdenum tetradecanoate.

The Mn:Mo atomic ratio of this fuel is about 11:05.

EXAMPLE 21 EXAMPLE 22 To base gasoline A is added 2.2 grams per gallon of manganese as (2-ethylhexylcyclopentadienyl)manganese tricarboriyl and 0.24 grams per gallon of molybdenum as molybdenum 4-methylbenzoate.

The MnzMo atomic ratio ofthis fuel is about 1:0.06.

EXAMPLE 23 To a base gasoline containing 100 percent aromatic hydrocarbons is added 2.0 grams per gallon of manganese as cyclopentadienylmanganese tricarbonyl and 1.4 grams per gallon of molybdenum as the molybdenum salt of tall 011 fatty acids.

The Mn:Mo atomic ratio of this fuel is about 120.4.

The small amount of organic molybdenum compound added to an organomanganese containing gasoline fuel signifi cantly reduces spark plug fouling caused by deposit formation on the plug ignition surfaces. The activity of the organic molybdenum compounds as spark plug antifoulants was determined in an actual engine test. The engine used was a single cylinder spark ignition engine. The test cycle used was to run the engine on the test fuel for 30 minutes with the throttle opened from 75 percent to 100 percent at 1,200 r.p.m.; the engine was then allowed to idle for sixty (60) seconds at 750 r.p.m. This cycle was repeated automatically until the engine stalled due to spark plug failure. The time to stall was recorded as Time to Failure."

Following are the results of a series of spark plug fouling tests run according to the test procedure set out above.

TABLE ll Molybdenum Compounds As Spark Plug Antifoulants Test Mn Mo Time to No. Fuel Composition gJgnl. gJgal. Failure 1 lsooctane Mn 2.0 17.0 hrs.

antiknock 2 Example 1 2.0 0.25 32.4 hrs.

3 Example 2 2.0 0.50 63.13 hrs.

Mn as (methylcyclopentadienyl)manganese tricarbonyl Me as Nuodex molybdenum naphthenate The data in table ll clearly illustrate the effectiveness of the molybdenum additives as spark plug antifoulants. The fuel composition (test 1) containing only the manganese primary antiknock caused spark plug failure after 17 hours. The addition of 0.25 g./gal. of Mo as molybdenum naphthenate increased time to failure up to 32.4 hours, a percent improvement in spark plug life; and 0.50 g./gal. of Mo as the naphthenate increased the time to failure to 63.8 hours, a 270 percent improvement in spark plug life.

Similar improvement in spark plug life is obtained when other organic molybdenum compounds, as disclosed herein, are added to gasoline fuels containing an organomanganese antiknock.

The present invention is embodied in (1) fuel compositions comprising a major portion of gasoline hydrocarbon, substantially free of tetrahydrocarbyl lead compounds, an antiknock amount of organomanganese compound and a spark plug antifoulant amount of an organic molybdenum compound, (2) concentrates containing the organomanganese compound and the organic molybdenum compound and (3) an improved method of operating a spark ignition engine. These embodiments have been described above. The invention is claimed as follows.

I claim:

1. A method of reducing spark plug fouling in an internal combustion engine caused by manganese-containing deposit formed on the firing surfaces of said spark plug from burning gasoline which comprises burning the gasoline characterized by being substantially free of tetrahydrocarbyl lead antiknock agents and containing (a) a cyclopentadienyl manganese tricarbonyl antiknock compound wherein said cyclopentadienyl group has up to 13 carbon atoms, and (b) a spark plug antifouling amount of organic molybdenum compound selected from the group consisting of molybdenum salts of a. phenol and C -C alkyl substituted phenols b. phosphoric acids having the formula where X, X, X and X are independently selected from 0 and S and R and R, are independently selected from hydrocarbon alkyl and aryl groups having from 1 to about 30 carbon atoms c. hydrocarbon carboxylic acids having from 5 to about 24 carbon atoms, and d. naphthenic acids.

2. The method of claim 1 wherein the amounts of said manganese antiknock compound and said organic molybdenum compound are sufficient to provide an atomic ratio of manganese: molybdenum from about 1:1 to about 1:0.05.

3. The method of claim 2 wherein said molybdenum compound is a molybdenum salt of phenol or alkyl substituted phenol.

4. The method of claim 2 wherein said molybdenum compound is a salt of said phosphoric acid.

5. The method of claim 2 wherein said'molybdenum compound is a salt ofsaid hydrocarbon carboxylic acid.

6. The method of claim 2 wherein said molybdenum compound is molybdenum naphthenate.

7. The method of claim 6 wherein said manganese tricarbonyl is (methylcyclopentadienyl)manganese tricarbonyl.

8. The method of claim 7 wherein said atomic ratio of manganese:molybdenum is from about 1:0.14 to about 1:0.07.

9. Gasoline substantially free of tetrahydrocarbyl lead antiknock agents containing from 0.5 to about 6.0 grams of manganese as a cyclopentadienyl manganese tricarbonyl antiknock compound wherein said cyclopentadienyl group has up to l3 carbon atoms and a spark plug antifouling amount of or ganic molybdenum compound selected from the group consisting of molybdenum salts of a. phenol and C,-C alkyl substituted phenols b. phosphoric acids having the formula where X, X, X and X are independently selected from O and S and R and R are independently selected from hydrocarbon alkyl and aryl groups having from 1 to about 30 carbon atoms c. hydrocarbon carboxylic acids having from 5 to about 24 carbon atoms, and d. naphthenic acids.

10. The gasoline composition of claim 9 wherein the amounts of said manganese antiknock compound and said organic molybdenum compound are sufficient to provide an atomic ratio of manganese:molybdenum from about 1:1 to about 1:005.

111. The gasoline composition of claim 10 wherein said molybdenum compound is a molybdenum salt of phenol or alkyl substituted phenol.

112. The gasoline composition of claim 10 wherein said molybdenum compound is a salt ofsaid phosphoric acid.

13. The gasoline composition of claim 10 wherein said molybdenum compound is a salt of said hydrocarbon carboxylic acid.

14. The gasoline composition of claim 10 wherein said molybdenum compound is molybdenum naphthenate.

115. The gasoline composition of claim M wherein said manganese tricarbonyl is (methylcyclopentadienyl) manganese tricarbonyl.

116. The gasoline composition of claim 15 wherein said atomic ratio of manganesezmolybdenum is from about l:0.l4 to about 12007.

17. The gasoline composition ofclaim 10 wherein said manganese tricarbonyl is (methylcyclopentadienyl) manganese tricarbonyl.

1%. The gasoline composition of claim 17 wherein said molybdenum compound is said molybdenum salt.

19. A method of reducing spark plug fouling in an internal combustion engine caused by manganese-containing deposit formed on the firing surface of said spark plug from burning gasoline which comprises burning the gasoline characterized by being substantially free of tetrahydrocarbyl lead antiknock agents and containing (a) a cycllopentadienyl manganese tricarbonyl antiknock compound wherein said cyclopentadienyl group has up to 13 carbon atoms and (b) a spark plug antifouling amount of a molybdenum chelate.

20. Gasoline substantially free of tetrahydrocarbyl lead antiknock agents containing from 0.5 to about 6.0 grams ofmanganese as cyclopentadienyl tricarbonyl antiknock compound wherein said cyclopentadienyl group has up to 13 carbon atoms and a spark plug antifouling amount of a molybdenum chelate.

21. The gasoline composition of claim 20 wherein the amounts of said manganese antiknlock compound and said molybdenum chelate are sufficient to provide an atomic ratio of manganesemolybdenum from about 1:1 to about 1:0.05.

Po-ww UNITED sTATEs PATENT OFFICE 569 CERTIFICATE OF CORRECTION Patent No. 3, 5,295 Dated October 97 Inventor) Vincent F. Hnizda It is certified that error appears in the above-identified patent and that said Letters Patent are hereby corrected as shown below:

In Column 1, lines 56-59, "P should read P I I R H In Column 5, line 60, "s-mol hdonum-s-di-,s" should I ead S-molybdenum-S 'S"di l- In Column 5, line 64,

S-molybdenu'm-O should read S-molYradenum-O O" In Column 4, line 9, "s-mol bdenum-s 'e' should read OInolyt denu1n-S,S' In Column 10, line 1 (Claim 19),

surface should read surfaces Signed and sealed this 16th day of May 1972.

(SEAL) Attest:

EDWARD M.FLEICHER, JR. ROBERT GOTTSCHALK Attesting Officer Commissioner of Patents 

2. The method of claim 1 wherein the amounts of said manganese antiknock compound and said organic molybdenum compound are sufficient to provide an atomic ratio of manganese: molybdenum from about 1:1 to about 1:0.05.
 3. The method of claim 2 wherein said molybdenum compound is a molybdenum salt of phenol or alkyl substituted phenol.
 4. The method of claim 2 wherein said molybdenum compound is a salt of said phosphoric acid.
 5. The method of claim 2 wherein said molybdenum compound is a salt of said hydrocarbon carboxylic acid.
 6. The method of claim 2 wherein said molybdenum compound is molybdenum naphthenate.
 7. The method of claim 6 wherein said manganese tricarbonyl is (methylcyclopentadienyl)manganese tricarbonyl.
 8. The method of claim 7 wherein said atomic ratio of manganese: molybdenum is from about 1:0.14 to about 1:0.07.
 9. Gasoline substantially free of tetrahydrocarbyl lead antiknock agents containing from 0.5 to about 6.0 grams of manganese as a cyclopentadienyl manganese tricarbonyl antiknock compound wherein said cyclopentadienyl group has up to 13 carbon atoms and a spark plug antifouling amount of organic molybdenum compound selected from the group consisting of molybdenum salts of a. phenol and C1-C18 alkyl substituted phenols b. phosphoric acids having the formula where X, X1, X2 and X3 are independently selected from O and S and R and R1 are independently selected from hydrocarbon alkyl and aryl groups having from 1 to about 30 carbon atoms c. hydrocarbon carboxylic acids having from 5 to about 24 carbon atoms, and d. naphthenic acids.
 10. The gasoline composition of claim 9 wherein the amounts of said manganese antiknock compound and said organic molybdenum compound are sufficient to provide an atomic ratio of manganese:molybdenum from about 1:1 to about 1:0.05.
 11. The gasoline composition of claim 10 wherein said molybdenum compound is a molybdenum salt of phenol or alkyl substituted phenol.
 12. The gasoline composition of claim 10 wherein said molybdenum compound is a salt of said phosphoric acid.
 13. The gasoline composition of claim 10 wherein said molybdenum compound is a salt of said hydrocarbon carboxylic acid.
 14. The gasoline composition of claim 10 wherein said molybdenum compound is molybdenum naphthenate.
 15. The gasoline composition of claim 14 wherein said manganese tricarbonyl is (methylcyclopentadienyl) manganese tricarbonyl.
 16. The gasoline composition of claim 15 wherein said atomic ratio of manganese:molybdenum is from about 1:0.14 to about 1: 0.07.
 17. The gasoline composition of claim 10 wherein said manganese tricarbonyl is (methylcyclopentadienyl) manganese tricarbonyl.
 18. The gasoline composition of claim 17 wherein said molybdenum compound is said molybdenum salt.
 19. A method of reducing spark plug fouling in an internal combustion engine caused by manganese-containing deposit formed on the firing surface of said spark plug from burning gasoline which comprises burning the gasoline characterized by being substantially free of tetrahydrocarbyl lead antiknock agents and containing (a) a cyclopentadienyl manganese tricarbonyl antiknock compound wherein said cyclopentadienyl group has up to 13 carbon atoms and (b) a spark plug antifouling amount of a molybdenum chelate.
 20. Gasoline substantially free of tetrahydrocarbyl lead antiknock agents containing from 0.5 to about 6.0 grams of manganese as cyclopentadienyl tricarbonyl antiknock compound wherein said cyclopentadienyl group has up to 13 carbon atoms and a spark plug antifouling amount of a molybdenum chelate.
 21. The gasoline composition of claim 20 wherein the amounts of said manganese antiknock compound and said molybdenum chelate are sufficient to provide an atomic ratio of manganese:molybdenum from about 1:1 to about 1:0.05. 